1. Field of the Invention
The present invention relates to an ink jet printer, and more particularly to a driving mechanism for driving a wiper and a purge pump.
2. Description of the Related Art
There has been known a conventional ink jet head formed with a plurality of ink chambers and a plurality of nozzles in a one-to-one correspondence with the ink chambers. The condition of ink in the nozzles and the ink chambers can degrade over time when dust mixes in the ink, when the solvent of the ink evaporates, or for other reasons. This degradation of ink condition can result in a portion of the nozzles ejecting ink improperly.
Ink jet printers including such an ink jet head have recently been provided with recovery mechanisms for returning the poor condition of ink in nozzles to a good condition. Such recovery mechanisms include wiper devices and suction purge devices. The wiper devices wipe the nozzle surface of the ink jet head. The suction purge devices cover the nozzle surface with a suction cap and operate a suction pump to suck ink from the nozzles through the suction cap.
U.S. Pat. No. 4,380,770 to Maruyama discloses an ink jet printer including pumped-forced circulation of ink through the head and the suction cap which together eliminate gas from the ink supply and overcome ink stagnation which adversely affect printing quality. This printer requires a pump for producing the forceful ink flow.
However, an ink jet printer with a recovery mechanism must include drive mechanisms for driving the different devices of the recovery mechanism. For example, a drive mechanism is required for driving the wiper device and motors are required for driving the suction purge device and the ink flow pump. All of these drive mechanisms undesirably increase the size and production cost of the ink jet printer.
Also, if a single motor is shared to drive more than one of the devices, the timing for driving one device is restricted by the timing for driving the other devices. The devices cannot be efficiently operated, so that the print cycle time increases. This prevents increasing the printing speed.
It is an object of the present invention to overcome the above-described problems, and provide a printing device capable of preventing ink ejection problems without increasing the size of the printer.
To achieve the above and other objects, there is provided an ink jet printer that has a basic structure including a printer body, a head unit, a pump, a wiper member, a motor, and a drive mechanism. The head unit is detachably mounted on the printer body and has an ink head formed with a plurality of ink chambers. The ink head has a nozzle surface formed with a plurality of nozzles fluidly connected to respective ones of the plurality of ink chambers individually. The pump is provided for adjusting an ink condition in the ink head. The wiper member is provided for wiping the nozzle surface of the ink head. The drive mechanism operatively connects the motor to the pump and the wiper member. The pump and the wiper member are driven in phase-dependent on rotations of the motor rotating in a predetermined direction.
The drive mechanism can include a transmission gear for transmitting driving force of the motor, a first gear rotatably disposed to meshingly engage the transmission gear, and a second gear rotatably disposed to meshingly engage the transmission gear. The first gear is formed with a cam groove for driving the wiper member. Rotations of the second gear drives the pump.
An adjustment mechanism can further be provided for adjusting rotational timings of the first gear and the second gear. The first gear and the second gear have a diameter equal to each other and are in concentric with each other. Each of the first gear and the second gear has a non-geared portion. The adjustment mechanism may include a first abutment portion formed in the first gear and a second abutment portion formed in the second gear. When the first abutment portion and the second abutment portion are in abutment with each other while one of the first gear and the second gear is stopped and remaining one of the first gear and the second gear is rotated, the one of the first gear and the second gear is urged by and rotated with the remaining one of the first gear and the second gear. The first abutment portion and the second abutment portion are brought into abutment with each other while the non-geared portion of one of the first gear and the second gear faces the transmission gear with the one of the first gear and the second gear being stopped, the one of the first gear and the second gear is urged by and rotated with the remaining one of the first gear and the second gear. The first abutment portion and the second abutment portion are brought into non-abutment with each other when the non-geared portion of the remaining one of the first gear and the second gear faces the transmission gear.
With respect to the basic structure, there can further be provided an ink supply source storing ink, a first ink channel for supplying the ink in the ink supply source to the head unit, and a second ink channel for feeding back ink in the head unit to the ink supply source. The pump is disposed in the second ink channel and generates a flow of ink from the head unit to the ink supply source when driven and interrupts the flow of ink when stopped.
It is desirable to stop the pump when ink droplets are elected from any one of the plurality of nozzles.
The ink supply source may include an ink cartridge detachably mounted on the ink jet printer body, a third ink channel, and a sub-tank fluidly connected to the ink cartridge through the third ink channel. The sub-tank stores ink supplied from the ink cartridge. In this configuration, an ink supply pump may further be provided. The ink supply pump is disposed in the third ink channel and generates a flow of ink from the ink cartridge to the sub-tank when driven and interrupts the flow of ink when stopped. The first ink channel supplies the ink of the sub-tank to the head unit, and the second ink channel feeds back the ink stored in the head unit to the sub-tank.
It is desirable that the pump be not driven during wiping operation of the wiper member.
With respect to the basic structure, there may further be provided a suction cap movable toward the head unit to hermetically seal the plurality of nozzles. The pump is fluidly connected to the suction cap. The pump sucks ink in the plurality of ink chambers through the suction cap. It is desirable that the pump be stopped when the pump sucks ink in the plurality of ink chambers through the suction cap.